Magneto breaker cam



octz, 1945. J. -R. HARKNESS VMAGNETVO BREAKER CAM Filed May. 29, 1944' 1"@Invenbor: g JosephRHarkness,

J His Attorney Patented Oct. 2, 1945 MAQNETO BREAKER CAM i Joseph R.Harkness; Schenectadm N. Y., assignor V ,to General Electric Company, acorporation of 1 Applica'tion'May 29,

1944, Serial No. 537,896

. s claims. (01. 74-467) My invention relates-to magneto breaker camsand particularly to a cam having a large number of lobes foroperating'the breaker of an' ignition system for a multiple cylinder"engine;

An object of my inventionis to provide an improved multiple lobe cam.

tion will become apparent and my invention will be better understoodfrom the following description referring to the accompanying drawing,and the features of novelty which characterize my invention will bepointed out with particularity in the claims annexed to and forming partof this specification.

In the drawing, Fig. 1 is an end view of a multiple lobe cam providedwith an embodiment of my invention; Fig. 2 is a sectional view takenalong line 22 of Fig. 1;- and Fig. 3 is an exploded perspective view ofthe two members which form the cam shown in Figs. 1 and 2.

Referring to the drawing, I have shown an embodiment of my improvedmultiple lobe breaker cam which comprises a pair of interdigitatedmembers formed of internal supporting hubportions I and 2 with aplurality of fingers 3 and 4 extending axially from about the hub inopposite directions towards each other from the hubs. These fingers 3and 4 are each formed with a radially raised axially extending ridgepart 5 intermediatethe sides 6 of the fingers, and the two members areadapt ed to be assembled together with the ends of the fingers from onehub extending telescopically over the outer periphery of the hub of theother member between the fingers of the other member. In order tosupport the cam in a definite position on a drive shaft, the hub of eachmember is formed with a central axially splined opening with the splinesI formed and arranged for axial alignment when the two members are. inassembled relationship, as shown in Figs. 1 and 2. In the manufacture of,a multiple lobe cam of relatively small diameter, it is very diflicultand expensive to make the lobes accurately on the surface of a cam, asit requires the use of a very small grinding wheel which tends to wearaway very rapidly. A cam according to my invention can be made of arelatively small diameter and is adapted to operate a single breaker foran ignition system requ ring a large number of spark discharges perrevolution of the cam, and a relatively much larger size grinding Wheelcan be used to form the lobes 5 than if these same size lobes were to beout on the surface of a single blank. Thus,

in'the arrangement shown in the figures each member is formed of ninefingers, an'd the assembly of the two nine-finger membersprovides acompact eighteen-lobe cam of desirable relatively" small diameter, whilethe f splinedf inner hub surface provides fori-a s'ecure connectionofthe cam to a drive shaft while providing a sufficiently large hubsection between the slots formed between the bases of the fingers andthe bases of the splines to provide adequate strength to each hub. Thenumber of fingers can be varied to provide any desired number of lobes,and the number of splines can be varied according to the diameter of thecam and the diameter of the drive shaft for the cam to providethedesired section to each hub for the required hub strength and the forceto be transmitted from the shaft to the fingers.

While I have illustrated and described a particular embodiment of myinvention, modifications thereof will occur to those skilled in the art.I desire. it to be understood, therefore, that my invention is not to belimited to the particular arrangement disclosed, and I intend in theappended claims to cover all modifications which do not depart from thespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. A multiple lobe breaker cam comprising a pair of interdigitatedmembers each having a plurality of fingers extending axially from asupporting hub and being formed with a radially raised axially extendingpart on the outer surface thereof providing the lobes of said cam.

2. A multiplelobe breaker cam comprising a pair of interdigitatedmembers each having a plurality of fingers extending axially from asupporting hub and being formed with a radially raised part on the outersurface intermediate the sides thereof providing the lobes of said cam,said members being arranged with the fingers extending towards eachother from said hubs.

' 3. A multiple lobe breakercam comprising a pair of interdigitatedmembers each having a plurality of fingers extending axially from asupporting hub and being formed with a radially raised axially extendingpart on the outer surface intermediate the sides thereof providing thelobes of said cam, said members being arranged with the fingersextending in opposite directions towards each other from said hubs.

4. A multiple lobe breaker cam comprising a pair of interdigitatedmembers each having a plurality of fingers extending axially from asupporting hub and being formed with a radially raised ridge on theouter surface thereof providing the lobes of said cam, each of said hubshaving a central axially splined opening with the splines formed andarranged for axial alignment when said members are in assembledrelationship. I

5. A multiple lobe breaker cam comprising a pair of interdigitatedmembers each having a plurality of fingers extending axially from aboutan internal supporting hub and being formed with a radially raisedaxially extending part on the outer surface thereof providing the lobesof said cam, said members being arranged with the fingers extending inopposite directions towards each other from said hubs and telescopicallyover the hub of the other of said members.

6. A multiple lobe breaker cam comprising a pair of 'interdigitatedmembers each having a plurality of fingers extending axially from asupporting hub and being formed with a radially raised axially extendingpart on the outer surface intermediate the sides thereof providing thelobes of said cam, said members being arranged with the fingersextending in opposite directions towards each other from said hubs, eachof said hubs having a central axially splined opening with the splinesformed and arranged for axial alignment when said members are inassembled relationship.

7. A multiple lobe breaker cam comprising a pair ofinterdigitated'members each having a plurality of fingers extendingaxially from about an internal supporting hub and being formed with aradially raised ridge on the outer surface thereof providing the lobesof said cam, said members being arranged with the fingers extending inopposite directions towards each other from said hubs with the ends ofthe fingers of each member radially over the hub of the other member,each of said hubs having a central axially splined opening with thesplines formed and arranged for axial alignment when said members are inassembled relationship.

8. An eighteen-lobe cam comprising a pair of interdigitated members eachhaving nine fingers extending axially from a supporting hub and beingformed with a radially raised axially extending ridge on the outersurface intermediate the sides thereof providing the lobes of said cam,said lfingers extending in opposite directions towards each other fromsaid hubs.

JOSEPH R. HARKNESS.

